Merge pull request #1592 from vmware-tanzu/jtc/add-auth0-integration-guide

Add How To... Integrate with Auth0

site/content/docs/howto/configure-supervisor-with-auth0.md

@@ -0,0 +1,148 @@
+---
+title: Configure the Pinniped Supervisor to use Auth0 as an OIDC provider
+description: Set up the Pinniped Supervisor to use Auth0 login.
+cascade:
+  layout: docs
+menu:
+  docs:
+    name: Configure Supervisor With Auth0 OIDC
+    weight: 80
+    parent: howtos
+---
+The Supervisor is an [OpenID Connect (OIDC)](https://openid.net/connect/) issuer that supports connecting a single
+"upstream" identity provider to many "downstream" cluster clients.
+
+This guide shows you how to configure the Supervisor so that users can authenticate to their Kubernetes
+cluster using their Auth0 credentials.
+
+## Prerequisites
+
+This how-to guide assumes that you have already [installed the Pinniped Supervisor]({{< ref "install-supervisor" >}}) with working ingress,
+and that you have [configured a FederationDomain to issue tokens for your downstream clusters]({{< ref "configure-supervisor" >}}).
+
+## Create an Auth0 Application
+
+Follow the instructions to [create an application](https://auth0.com/docs/get-started/auth0-overview/create-applications).
+
+For example, to create an app:
+
+1. In the [Auth0 Admin Console](https://manage.auth0.com/), navigate to _Applications_ > _Applications_.
+2. Create a new application:
+   1. Click `+ Create Application`.
+   2. Provide a name. For `Choose an application type`, select `Regular Web Applications`.
+   3. Under `Settings`:
+      1. Note the `Client ID` and `Client Secret`, which will be provided later to Pinniped.
+      2. Update `Allowed Callback URLs` with Pinniped's issuer URL, appending `/callback` to the end. (Example: `https://pinniped.issuer.example.com/callback).
+      3. Under `Advanced Settings`:
+         1. Choose `Grant Types` and make sure that `Authorization Code`, `Refresh Token`, and `Password` are selected.
+         2. Find the Auth0 Issuer URL by loading the URL at `Endpoints` > `OAuth` > `OpenID Configuration` and finding the `"issuer"` field.
+
+## Configure Auth0 to include user groups in its ID tokens
+
+Auth0 does not have a simple concept of group membership for users.
+It may be possible to model group membership in Auth0, but the specifics depend on which enterprise connector or database is used to create your users.
+Please refer to the Auth0 documentation for more information.
+
+Pinniped does not have a specific recommendation for how user groups are defined in Auth0.
+The examples below are provided as examples to better understand how Auth0 and Pinniped integrate, not how to configure Auth0.
+
+Assuming that you have somehow configured Auth0 to include group membership information about your users, you can expose this to Pinniped by configuring Auth0 to include a [custom claim](https://auth0.com/blog/adding-custom-claims-to-id-token-with-auth0-actions/) in the Auth0 ID token.
+
+Auth0 recommends using a [namespaced format](https://auth0.com/docs/secure/tokens/json-web-tokens/create-custom-claims) for your custom claim names.
+In the following example, replace `"https://example.com/pinniped/groups"` with the namespaced claim name of your choice.
+Pinniped requires that the value of the group claim is an array of strings.
+
+The following example is intended to show how to add a custom claim, but does not show a realistic example of where the group names should come from.
+To keep this example simple, the group names shown here are hardcoded.
+Do not hardcode group names for a production system.
+Instead, the array of groups should be dynamically provisioned from the appropriate place in the Auth0 user store.
+
+```typescript
+exports.onExecutePostLogin = async (event, api) => {
+  if (event.authorization) {
+    api.idToken.setCustomClaim("https://example.com/pinniped/groups", ["auth0-read-only", "other-grouo", "something-else"]);
+  }
+};
+```
+
+To configure your Kubernetes authorization, please see [how-to login]({{< ref "login" >}}).
+
+## Configure the Supervisor
+
+Create an [OIDCIdentityProvider](https://github.com/vmware-tanzu/pinniped/blob/main/generated/{{< latestcodegenversion >}}/README.adoc#oidcidentityprovider) in the same namespace as the Supervisor.
+
+For example, this OIDCIdentityProvider uses Auth0's `email` claim as the Kubernetes username:
+
+```yaml
+apiVersion: idp.supervisor.pinniped.dev/v1alpha1
+kind: OIDCIdentityProvider
+metadata:
+  namespace: pinniped-supervisor
+  name: auth0
+spec:
+
+  # Change this to be the actual issuer provided by your Auth0 account.
+  issuer: https://<your-tenant-id>.<your-region>.auth0.com/
+
+  authorizationConfig:
+
+    # Request any scopes other than "openid" for claims besides
+    # the default claims in your token. The "openid" scope is always
+    # included.
+    additionalScopes: 
+      - offline_access
+      - email
+
+    # If you would also like to allow your end users to authenticate using
+    # a password grant, then change this to true. Password grants only work
+    # with applications created in Auth0 with the "Password" grant type enabled.
+    allowPasswordGrant: false
+
+  # Specify how Auth0 claims are mapped to Kubernetes identities.
+  claims:
+
+    # Specify the name of the claim in your Auth0 ID token that will be mapped
+    # to the "username" claim in downstream tokens minted by the Supervisor.
+    username: email
+
+    # Specify the name of the claim in your Auth0 ID token that represents the
+    # groups that the user belongs to.
+    groups: https://example.com/pinniped/groups
+
+  # Specify the name of the Kubernetes Secret that contains your Auth0
+  # application's client credentials (created below).
+  client:
+    secretName: auth0-client-credentials
+
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  namespace: pinniped-supervisor
+  name: auth0-client-credentials
+type: secrets.pinniped.dev/oidc-client
+stringData:
+
+  # The "Client ID" that you got from Auth0.
+  clientID: "<your-client-id>"
+
+  # The "Client secret" that you got from Auth0.
+  clientSecret: "<your-client-secret>"
+```
+
+Note that the `metadata.name` of the OIDCIdentityProvider resource may be visible to end users at login prompts
+if you choose to enable `allowPasswordGrant`, so choose a name which will be understood by your end users.
+For example, if you work at Acme Corp, choose something like `acme-corporate-auth0` over `my-idp`.
+
+Once your OIDCIdentityProvider has been created, you can validate your configuration by running:
+
+```shell
+kubectl describe OIDCIdentityProvider -n pinniped-supervisor auth0
+```
+
+Look at the `status` field. If it was configured correctly, you should see `phase: Ready`.
+
+## Next steps
+
+Next, [configure the Concierge to validate JWTs issued by the Supervisor]({{< ref "configure-concierge-supervisor-jwt" >}})!
+Then you'll be able to log into those clusters as any of the users from the Auth0 directory.